1. Field of the Invention
The present invention is related to hearing systems, devices and methods. Although specific reference is made to hearing aid systems, embodiments of the present invention can be used in many applications in which a signal is used to stimulate the ear.
People like to hear. Hearing allows people to listen to and understand others. Natural hearing can include spatial cues that allow a user to hear a speaker, even when background noise is present. People also like to communicate with those who are far away, such as with cellular phones.
Hearing devices can be used with communication systems to help the hearing impaired and to help people communicate with others who are far away. At least some hearing impaired people have a mixed hearing loss. With mixed hearing loss, a person may have a conductive hearing loss that occurs in combination with a sensorineural hearing loss. The conductive hearing loss may be due to diminished function of the conductive components of the ear such as the eardrum and ossicles that transmit sound from the ear canal to the cochlea. The sensorineural hearing loss may comprise diminished function of the cochlea, such that the cochlea does not convert sound waves to neural impulses as effectively as would be ideal.
Many of the prior therapies for mixed hearing loss and sensorineural hearing loss are less than ideal in at least some instances. One approach has been to replace, at least partially, one or more of the ossicles of the middle ear with an ossicular replacement prosthesis. Although the ossicular replacement prosthesis can improve the conductive portion of the mixed hearing loss, such treatment may leave the patient with diminished hearing due to the remaining sensorineural hearing loss in at least some instances.
Prior acoustic hearing devices such as conventional in the ear or behind the ear hearing aids may not be effective with patients having conductive hearing loss in at least some instances. For example, the patient may have atresia, which is an absence of the ear canal or failure of the canal to be tubular or fully formed. Further, such prior acoustic hearing devices can cause feedback at high frequencies and the frequency response may be limited to about 4 kHz such that sound localization cues may not be present with such devices in at least some instances.
A bone-anchored hearing aid (hereinafter “BAHA™”) has been used to provide sound based on bone conduction. The bone-anchored devices can be suited to people who have conductive hearing losses, unilateral hearing loss and people with mixed hearing losses. Such people may not be well served with in the ear or behind the ear hearing aids. However, bone conduction hearing devices may not offer sound localization to the user in at least some instances, such that at least some people may not be able localize the source of sound in at least some instances. This lack of sound localization may make hearing difficult for the user in at least some instances. Also, with bone conduction hearing aids, a post may be surgically embedded into the skull with a small abutment extending through the skin, such that implantation of the device can be somewhat invasive and the post through the skin can be at risk for infection in at least some instances.
For the above reasons, it would be desirable to provide hearing systems which at least decrease, or even avoid, at least some of the above mentioned limitations of the prior prosthetic devices. For example, there is a need to provide a hearing prosthesis which provides hearing with natural qualities, for example with spatial information cues, and which allow the user to hear with less occlusion, distortion and feedback than the prior devices.
2. Description of the Background Art
Patents and publications that may be relevant to the present application include: U.S. Pat. Nos. 3,585,416; 3,764,748; 3,882,285; 4,498,461; 5,142,186; 5,360,388; 5,554,096; 5,624,376; 5,795,287; 5,800,336; 5,825,122; 5,857,958; 5,859,916; 5,888,187; 5,897,486; 5,913,815; 5,949,895; 6,005,955; 6,068,590; 6,093,144; 6,139,488; 6,174,278; 6,190,305; 6,208,445; 6,217,508; 6,222,302; 6,241,767; 6,422,991; 6,475,134; 6,519,376; 6,620,110; 6,626,822; 6,676,592; 6,728,024; 6,735,318; 6,900,926; 6,920,340; 7,072,475; 7,095,981; 7,239,069; 7,289,639; D512,979; 2002/0086715; 2003/0142841; 2004/0234092; 2005/0020873; 2006/0107744; 2006/0233398; 2006/075175; 2007/0083078; 2007/0191673; 2008/0021518; 2008/0107292; commonly owned U.S. Pat. Nos. 5,259,032; 5,276,910; 5,425,104; 5,804,109; 6,084,975; 6,554,761; 6,629,922; U.S. Publication Nos. 2006/0023908; 2006/0189841; 2006/0251278; and 2007/0100197. Non-U.S. patents and publications that may be relevant include EP1845919 PCT Publication Nos. WO 03/063542; WO 2006/075175; U.S. Publication Nos. Journal publications that may be relevant include: Ayatollahi et al., “Design and Modeling of Micromachines Condenser MEMS Loudspeaker using Permanent Magnet Neodymium-Iron-Boron (Nd—Fe—B)”, ISCE, Kuala Lampur, 2006; Birch et al, “Microengineered Systems for the Hearing Impaired”, IEE, London, 1996; Cheng et al., “A silicon microspeaker for hearing instruments”, J. Micromech. Microeng., 14 (2004) 859-866; Yi et al., “Piezoelectric microspeaker with compressive nitride diaphragm”, IEEE, 2006, and Zhigang Wang et al., “Preliminary Assessment of Remote Photoelectric Excitation of an Actuator for a Hearing Implant”, IEEE Engineering in Medicine and Biology 27th Annual Conference, Shanghai, China, Sep. 1-4, 2005. Other publications of interest include: Gennum GA3280 Preliminary Data Sheet, “Voyager TDTM. Open Platform DSP System for Ultra Low Power Audio Processing” and National Semiconductor LM4673 Data Sheet, “LM4673 Filterless, 2.65W, Mono, Class D audio Power Amplifier”; Puria, S. et al., Middle ear morphometry from cadaveric temporal bone micro CT imaging, Invited Talk. MEMRO 2006, Zurich; Puria, S. et al, A gear in the middle ear ARO 2007, Baltimore, Md.; and Lee et al., “The Optimal Magnetic Force For A Novel Actuator Coupled to the Tympanic Membrane: A Finite Element Analysis,” Biomedical Engineering: Applications, Basis and Communications, Vol. 19, No. 3(171-177), 2007; Stenfelt & Goode, Otology & Neurology, 26:1245-1261, 2005.
For the above reasons, it would be desirable to provide hearing systems which at least decrease, or even avoid, at least some of the above mentioned limitations of the prior hearing devices. For example, there is a need to provide a comfortable hearing device which provides hearing with natural qualities, for example with spatial information cues, and which allow the user to hear with less occlusion, distortion and feedback than prior devices.